From the seven-year itch to the end of the affair, our culture is stuffed with bywords for when love's frenzies subside, and people say things such as, "It's not you, it's me" and pack a holdall. Now researchers at the University of Pavia, in Italy, may have discovered why: it's all to do with levels of protein called nerve growth factor (NGF), which causes the sweaty palms, fluttering hearts and all that stuff. Studying couples who claimed to be "truly, madly and deeply in love", Dr Enzo Emanuele and his team found that those who had just met were brimming with NGF, whereas people who had been together for a year or more had much the same levels as the unattached.

For the romantically inclined, this may be bad news: all that magic reduced to metabolic processes and the contention that once you are past the 12-month mark, crazed excitement might be beyond your reach.

To use the philosophical vernacular, all this is a glaring example of the dried-up credo known as materialism - in the words of the Oxford English Dictionary, "the opinion that nothing exists but matter and its movements and modifications". Whether it advances our understanding of the mating game is doubtful: give or take the biochemical stuff, doesn't the research simply serve to remind us that the can't-keep-your-hands-off-each-other phase doesn't last forever and that the L-word goes on to define something a bit more profound?

In fact, just to raise the flag for cornball romanticism, let us risk ridicule and finish with a passage that is increasingly popular at weddings: "Love is not breathlessness, it is not excitement, it is not the promulgation of eternal passion. That is just being 'in love', which any fool can do. Love itself is what is left over when being in love has burned away, and this is both an art and a fortunate accident. Those that truly love have roots that grow towards each other ... and when all the pretty blossom has fallen from their branches, they find that they are one tree and not two."

That's from Captain Corelli's Mandolin. It probably tells you a bit more than Emanuele's research.